1. Field of the Invention
The present invention has as its object a process for the continuous production of viscose rayon yarns. More particularly it has as its object a simplified process for the continuous production of viscose rayon yarns having a high degree of whiteness (degree of white).
2. Prior Art
As is known, the continuous spinning of viscose rayon occurs through a rather complex series of treatments, which may advantageously take place while the yarn travels in a substantially helical path, viz. travels while it is wound onto rollers which are askew with respect to one another. A plurality of yarns may be concurrently treated on a single spinning machine, in this type of process, such as taught e.g. in a copending Italian application of the same applicant, No. 28324 A/78.
If the viscose rayon yarn which is obtained is to be used for textile purposes, it must have a certain degree of white, which can be measured by standard tests which will be discussed later. To this end the yarn, after having undergone coagulation in a coagulating bath, is typically subjected to setting, desulphurating, bleaching, finishing and various washings, besides a final drying. Desulphuration and bleaching are indispensable to obtain an adequate degree of white.
The art has sought for some time to improve this classic treatment, on the one hand by speeding it up, on the other by reducing the space take-up of the spinning machines, or in both ways. It has already been proposed to reduce the number of treatments by tolerating a lower degree of white, but the resulting yarn is only acceptable for some applications. The present invention solves the problem of simplifying the viscose rayon continuous spinning process, permitting accelerating it and/or reducing the space take-up of the spinning machines, without sacrificing an excellent degree of white, and, on the contrary, while obtaining a degree of white which is higher than that commonly accepted, and all this by extremely simple and economical means.